When to use displacement, velocity or acceleration amplitude units in vibration analysis?

A novice vibration analyst always has a question whether to use displacement, velocity or acceleration amplitude unit? Here is a rule of thumb based on the frequency.
Displacement is a good measure at lower frequencies especially less than 5 Hz. The failure mode is generally the “stress” causing due to the displacement. Velocity measures how often the displacement is being applied in a given time period. It is related to the fatigue mode of failure. Velocity amplitude unit is a good measure in the range of 5-2000 Hz frequency. Even at small displacement amplitude the repeated motion can cause fatigue failure. Above the 2000 Hz the failure is normally force related. Acceleration is measure of the likelihood of force being the mode of failure.

There are areas on chart where stress, fatigue and force related failures overlap. The proper selection of amplitude unit will depend upon the application under study. Note that frequency, displacement, velocity and acceleration are related. Knowing any 2 quantities, other variables can be easily calculated.

Picture reference: www.vibrationschool.com

Open Source Manufacturing

The open source software community has grown exponentially over the past several years, and it continues to do so along with expanding to previously closed source territory. More and more processes once run by closed source software are moving in the direction of open source software to take advantage of the reliability, accessibility and lower cost. One very well known open source software bundle is the LAMP stack for building software applications. Each portion (L-Linux, A-Apache, M-MySQL, P-PHP) is open source and free for anyone to obtain, and more and more companies are using it as a medium for creating software applications. However the manufacturing community has failed to embrace these changes and lower the costs associated with manufacturing information technology. Manufacturing continues to remain closed source, proprietary and non-scalable.
In this effect, we demonstrate the manufacturing open source stack ULMF (U-Ubuntu, L –LinuxCNC, M-MTConnect, F-Firefox) to create an open source bundle for use in the manufacturing world. ULMF is developed as part of the supervisory system thrust area for the Smart Machine Platform Initiative (SMPI). The supervisory system is defined as a system that integrates and coordinates multiple process monitoring and control modules such that a globally optimal machining solution could be delivered real-time for desired quality and maximum productivity.In this paper, we will lay out the methods to use open source applications to create a functional CNC control that is capable of obtaining and displaying data using Ubuntu operating system, LinuxCNC-EMC (Enhanced Machine Controller), MTConnect and Firefox internet browser. MTConnect is a royalty-free open communication standard for interconnect ability in the manufacturing arena. The free and open standard allows devices and systems to send out understandable information in the required format. Architecture of the ULMF stack and MTConnect standard is explained in depth. This paper explains why an open source bundle is important to the manufacturing community as well as the potential ramifications of using open source to apply to manufacturing data management solutions. The potential benefits include knowledge management, real-time data access, scalability, plug-and-play functionality and data mining capabilities.

Reference: Open Source Manufacturing, 2009 conference of the Society For Machinery Failure Prevention Technology, Dayton, Ohio, 28-30 April 2009.
Authors: Pierce Kuhnell, Amit Deshpande

MTConnect - Directory of Resources

The first directory of resources is released. It is a listing of companies working to provide MTConnect offerings and services.

Hardware
Assembly and Test Worldwide
Bosch Rexroth Corporation
GE Fanuc Intelligent Platforms
MAG Industrial Automation Systems, MAG Cincinnati
Mazak Corporation
Parlec, Inc.

Software Applications
Bosch Rexroth Corporation
GE Fanuc Intelligent Platforms
Georgia Tech Factory Information Systems Lab
Great Technological Collaborations, Inc.
MacKintok Information Architects & Designers
MAG Industrial Automation Systems, MAG Cincinnati
Mazak Corporation
Parlec, Inc.
TechSolve, Inc.

Development Tools
Georgia Tech Factory Information Systems Lab
Great Technological Collaborations, Inc.
MacKintok Information Architects & Designers
TechSolve, Inc.
Consulting Services
Georgia Tech Factory Information Systems Lab
Great Technological Collaborations, Inc.
MacKintok Information Architects & Designers
TechSolve, Inc.

Training
Georgia Tech Factory Information Systems Lab
Great Technological Collaborations, Inc.
MacKintok Information Architects & Designers
TechSolve, Inc.

Simulation Games # 4: Problem-based Learning and Simulation Games

Simulation game based learning is an extension of the problem-based learning paradigm, having all its inherent characteristics plus some additional advantages. Simulation game and problem based learning are both experiential, collaborative, active learning and learner centric approaches. In simulation game, the instructor is a facilitator of learning process and students have the responsibility of learning as in problem-based learning. In problem-based learning, a self-assessment is conducted at the end of the problem or the learning cycle. On the other hand, simulation game has a scoring system that is the indication of one’s performance. Students are motivated to maximize their score by trying alternative strategies and read more literature. This is a significant advantage over problem-based learning. Secondly, simulation games are online computer based where student can learn as per his or her time at any place where there is an internet connection. Some studies have found that engineers are visual learners. Advanced graphics and multimedia may be used to capture the student’s attention. This observation calls for extensive use of simulation games especially in the light of decreasing computer technology cost and increasing speeds. Thirdly, some sort of online help is provided in simulation games. Thus, a student does not have to wait for the instructor to address the difficulty. Last and the most important advantage with simulation games is that they can save a lot of clerical work for students. The student can try out various strategies and alternatives and focus on the parameter of interest leaving the calculation and presentation work for the software. It is a more systematic and organized way of learning.